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March 2012

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From:
Steven Creswick <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Steven Creswick <[log in to unmask]>
Date:
Tue, 6 Mar 2012 15:15:50 -0500
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In the past, I had run into glob tops, encapsulants, and molding compounds containing alumina's, and silica's emitting alpha particles - and these would be immediately on top of the sensitive portion of the chip...!

Since then things have cleaned up a bit, and/or a thin layer of siloxane polyimde, or some such material could act as a alpha particle shield.

Depending on the package construction, I find it very interesting that the alpha particles coming from the solder joint could pass all the way through copper, underfill?, laminate material, or encapsulant/molding compounds and introduce soft errors, since just about anything stops an alpha particle. [not denying that solder can emit]

Is it REALLY the solder?


Steve Creswick
Sr Associate - Balanced Enterprise Solutions
http://www.linkedin.com/in/stevencreswick
                         616 834 1883



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Tuesday, March 06, 2012 2:07 PM
To: [log in to unmask]
Subject: Re: [TN] Fw: Help. Is this true-- SOFT ERRORS FROM SOLDER??

Tin whiskers is not the only issue with SAC solder in space programs. :-)


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of harvey
Sent: Tuesday, March 06, 2012 12:50 PM
To: [log in to unmask]
Subject: Re: [TN] Fw: Help. Is this true-- SOFT ERRORS FROM SOLDER??

Karen
I think that Mahendra cannot use SAC solder in space, because of those tin whiskers.
 




________________________________
From: Karen Tellefsen <[log in to unmask]>
To: [log in to unmask]
Sent: Tue, March 6, 2012 10:32:39 AM
Subject: Re: [TN] Fw: Help. Is this true-- SOFT ERRORS FROM SOLDER??

This is much more of a problem with tin-lead solder than SAC solder,
because naturally occurring lead emits a tiny amount of alpha particles.
It's mostly an issue with BGA spheres,some of which are high lead alloys,
and are often close to IC chips where the alpha emissions are most likely
to cause damage.,

Karen Tellefsen - Electrical Testing
[log in to unmask]
908-791-3069



                                                                            
                                                                            
                                                                            
  [TN] Fw: Help. Is this true-- SOFT ERRORS FROM SOLDER??                  
                                                                            
                                                                            
  harvey                                                                  
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            TechNet                                                        
                                                        03/06/2012 11:58 AM 
                                                                            
                                                                            
                                                                            
                                                                            
  Sent by:                                                                
          TechNet <[log in to unmask]>                                        
  Please respond to TechNet E-Mail Forum, harvey                      
                                                                            
                                                                            
                                                                            






Could this be true only of 63-37 or would lead-free SAC alloys also be
potentially guilty of causing soft errors?



----- Forwarded Message ----
From: "Gandhi, Mahendra S (AS)" <[log in to unmask]>
To: "[log in to unmask]" <[log in to unmask]>;
"[log in to unmask]" <[log in to unmask]>;
"[log in to unmask]" <[log in to unmask]>
Sent: Tue, March 6, 2012 8:38:40 AM
Subject: Help. Is this true??


Evidently regular solder has decaying Uranium in it, or somehow generates
alpha
particles, which are being blamed for upsets.  Some chips are moving to a
special “low alpha” solder internally to avoid this problem on
bump-grid-arrays
in  flipchip parts.

Mahendra Gandhi
SME - PWB Technologies
Aerospace Engineering
One Space Park, M5/1085A
Redondo Beach, Ca. 90278/*[log in to unmask]
(Office: 310.813.6857 Fax: 310.812.8630

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